default-value

问题 Given: class StringRecord : INotifyPropertyChanged { public string Key { get; set; } // real INPC implementation is omitted public string Value { get; set; } // real INPC implementation is omitted ... } class Container { public ObservableKeyedCollection<string, StringRecord> Params { get; set; } ... { The ObservableKeyedCollection is the one found here. A TextBox is bound to one of the collection items (DataContext is inherited): <TextBox Text="{Binding Params[APN_HOST].Value}"/> When I

问题 We are creating an user's editing data page, so the textfield already comes filled with the user data and users can change and save it... The problem is that when I start to enter character into textfield, the cursor get lost, every character that I enter (from the device keyboard), the cursor goes to the first character... and if I remove the controller with my initial value, it works fine, but then I can not have my textfield filled with the users data. Code sample: child: StreamBuilder

问题 I have a python option parsers that parses an optional --list-something option. I also want the --list-something option to have an optional argument (an option) Using the argument default="simple" does not work here, otherwise simple will always be the default, not only when --list-something was given. from optparse import OptionParser, OptionGroup parser = OptionParser() options = OptionGroup(parser, "options") options.add_option("--list-something", type="choice", choices=["simple",

问题 There's an exceptional case in WPF where I need to set a dependency property via XAML that actually doesn't get stored itself, but rather is used to set other dependency properties. This is pretty easy since I just use the CoerceValue to intercept the change, do what I want with the passed-in value, then cancel the change on that property. This means when I get that property, I'll still get the default value since I blocked the actual change. Works great. As an example, when I set this faux

问题 I am trying to auto-fill a form's input values. I have a function called load which need to load the data when a button is clicked. I've been working with redux form, and I need to use the Field component to work with the initialValues prop. However, every time I add it I get this error: "Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined

问题 I am trying to enter input from the console(street, city, country) but the fields are underlined and display the message(field is never assigned to and will have its value null). I have also created a method SetFullAddress which doesn't work(idk if it is because of that message). Code inside Address class: public class Address { private string street; private string city; private string country; public Address() { this.Street = street; this.City = city; this.Country = country; } public string

问题 I am curious about specific scenario in SQL when using EF Core. For example there is a column that allows null and at the same time has defalut value, it is unusual situation but that is not the issue here. Question is about technical possibility. [SomeId] [uniqueidentifier] NULL DEFAULT (newsequentialid()) And in Application there is Entity(Code First) which has appropriate Property public Guid? SomeId { get; set; } The problem is how to Insert this Entity into DB so that SomeId would have

问题 Let's say I have a table called "table" So Create Table "Table" (a int not null, b int default value 1) If I do a " INSERT INTO "Table" (a) values (1) ". I will get back 1 for column a and 1 for column b as the default value for column b is 1. BUT if I do " INSERT INTO "Table" (a, b) values (1, null) ". I will bet back 1 for column a and an empty value for column b. Is there a way to set a column's default value if a null was given? 回答1: No, if you are doing: INSERT INTO my_table (a, b)

问题 please see the link below : https://www.boot-loader.com/eng how does default password in that link work? how can i have a default value such as "password" string for textbox below (with asterisks) : <asp:TextBox ID="headertxtPassWord" runat="server" Text="password" CssClass="header-login-input" ValidationGroup="A" TextMode="Password"></asp:TextBox> 回答1: Ok I think I did not understand you correctly. Here you can find the answer with some background and explanation Basically the point is that

问题 When the application is first startet, I'd like to store all default values I've defined in my prefences.xml by using the 'android:defaultValue' attribute, but some of them are not stored on the device - can someone tell me why? <?xml version="1.0" encoding="utf-8"?> <PreferenceCategory android:title="@string/prefs_cat_title_x"> <ListPreference android:key="@string/prefs_key_1" android:title="@string/prefs_title_1" android:summary="@string/prefs_summary_1" android:entries="@array/array1"